• It is a layered system framework that helps the android OS manage hardware, apps and system processes.
• It was built in Linux.
• Android was developed by Android INC in 2003, founded by Andy Rubins, Rich Miner, Nick Sears and Christ White.
• Google accquired Andriod in 2005 and released the first version, Android 1.0 on Sep 23,2008.

Components of Android Architecture

Linux Kernel - The foundation

• Foundation of the android platform.
• Directly manages the hardware, including the CPU memory, camera, sensor, WiFi and other component.
• Handles process management deciding which apps and system service run and for how long and memory management, allocating and freeing RAM as needed.
• Provides security through SELinux enforcing restrictions to prevent apps from accessing resources they shouldn’t as it manages networking, including WiFi mobile data and VPN connections.

Hardware Abstraction Layer(HAL)

• Provides standard interfaces that allow Android framework to interact with device hardware.
• HAL modules are dedicated to a specific hardware component like camera, Bluetooth or GPS.
• When an API uses a hardware API, HAL translates it to the correct commands for the device’s hardware driver.
• HAL makes app work across different devices without worrying about hardware.

Android Runtime(ART)

• Android Runtime(ART) is the environment in which Android apps execute.
• Apps are complied into Dalvik Executable (DEX) bytecode, which ART runs efficiently optimizing for low memory usage.
• ART uses Ahead-of-Time(AOT) compilation during installation and Just-in-Time(JIT) compilation at runtime to improve performance.